1. Technical Field
The present invention relates to an image forming apparatus for forming a color image by superposing liquid developers of a plurality of different colors and a method of controlling an image forming apparatus. More particularly, the present invention relates to an image forming apparatus for forming a color image on a transfer medium by repeatedly executing a transfer step of transferring a developed image formed on an image carrier onto an intermediate transfer medium such as an intermediate transfer belt for a plurality of liquid developers.
2. Description of the Related Art
Various wet-developing image forming devices for developing a latent image by means of a high viscosity liquid developer prepared by dispersing solid toner into a liquid solvent to visualize an electrostatic latent image have been proposed. A developer to be used for such wet-developing image forming devices is prepared by suspending the solid component (toner particles) in an organic solvent (carrier liquid) of silicon oil, mineral oil, edible oil or the like that is electrically insulating and highly viscous. Toner particles are very fine and have a particle size of about 1 μm. Thus, wet-developing image forming devices can form high quality images if compared with dry-developing image forming devices designed to use powdery toner particles having a particle size of about 7 μm mainly because of such fine toner particles they employ.
While wet-developing image forming devices can produce high quality images because of fine toner particles they employ, it is known that their transfer efficiency shows temperature dependence so that it is believed that wet-developing image forming devices are less stable in terms of image forming performance if compared with dry-developing image forming devices. It is also known that optimum transfer conditions of a wet-developing image forming devices differ from recording medium to recording medium (coat paper, plain paper, etc.) onto which a toner image is transferred. The above-identified problems of wet-developing image forming devices designed to use liquid developers are described, for example, in JP-A-2000-275969. The patent document describes that those problems can be overcome by controlling the temperature of the transfer process.